Function builtin_normalize_path

v2/engine/builtins.c:1517–1646

LIST * builtin_normalize_path( FRAME * frame, int flags )
{
    LIST * arg = lol_get( frame->args, 0 );

    /* First, we iterate over all '/'-separated elements, starting from the end
     * of string. If we see a '..', we remove a preceeding path element. If we
     * see '.', we remove it. Removal is done by overwriting data using '\1'
     * characters. After the whole string has been processed, we do a second
     * pass, removing any entered '\1' characters.
     */

    string   in[ 1 ];
    string   out[ 1 ];
    /* Last character of the part of string still to be processed. */
    char   * end;
    /* Working pointer. */
    char   * current;
    /* Number of '..' elements seen and not processed yet. */
    int      dotdots = 0;
    int      rooted  = 0;
    OBJECT * result  = 0;
    LISTITER arg_iter = list_begin( arg );
    LISTITER arg_end = list_end( arg );

    /* Make a copy of input: we should not change it. Prepend a '/' before it as
     * a guard for the algorithm later on and remember whether it was originally
     * rooted or not.
     */
    string_new( in );
    string_push_back( in, '/' );
    for ( ; arg_iter != arg_end; arg_iter = list_next( arg_iter ) )
    {
        if ( object_str( list_item( arg_iter ) )[ 0 ] != '\0' )
        {
            if ( in->size == 1 )
                rooted = ( object_str( list_item( arg_iter ) )[ 0 ] == '/'  ) ||
                         ( object_str( list_item( arg_iter ) )[ 0 ] == '\\' );
            else
                string_append( in, "/" );
            string_append( in, object_str( list_item( arg_iter ) ) );
        }
    }

    /* Convert \ into /. On Windows, paths using / and \ are equivalent, and we
     * want this function to obtain a canonic representation.
     */
    for ( current = in->value, end = in->value + in->size;
        current < end; ++current )
        if ( *current == '\\' )
            *current = '/';

    /* Now we remove any extra path elements by overwriting them with '\1'
     * characters and cound how many more unused '..' path elements there are
     * remaining. Note that each remaining path element with always starts with
     * a '/' character.
     */
    for ( end = in->value + in->size - 1; end >= in->value; )
    {